School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, Beijing 100083, China.
School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China.
J Environ Sci (China). 2022 Mar;113:204-218. doi: 10.1016/j.jes.2021.05.032. Epub 2021 Jun 26.
NH-SCR performances were explored to the relationship between structure morphology and physio-chemical properties over low-dimensional ternary Mn-based catalysts prepared by one-step synthesis method. Due to its strong oxidation performance, Sn-MnOx was prone to side reactions between NO, NH and O, resulting in the generation of more NO and NO, here most of NO was driven from the non-selective oxidation of NH, while a small part generated from the side reaction between NH and NO. Co or Ni doping into Sn-MnOx as solid solution components obviously stronged the electronic interaction for actively mobilization and weakened the oxidation performance for signally reducing the selective tendency of side reactions to NO. The optimal modification resulted in improving the surface area and enhancing the strong interaction between polyvalent cations in Co/Ni-Mn-SnO to provide more surface adsorbed oxygen, active sites of Mn and Mn, high-content Sn and plentiful Lewis-acidity for more active intermediates, which significantly broadened the activity window of Sn-MnOx, improved the N selectivity by inhibiting NO formation, and also contributed to an acceptable resistances to water and sulfur. At low reaction temperatures, the SCR reactions over three catalysts mainly obeyed the typical Elye-rideal (E-R) routs via the reactions of adsorbed l-NHx (x = 3, 2, 1) and B-NH with the gaseous NO to generate N but also NO by-products. Except for the above basic E-R reactions, as increasing the reaction temperature, the main adsorbed NOx-species were bidentate nitrates that were also active in the Langmuir-Hinshelwood reactions with adsorbed l-NHx species over Co/Ni modified Mn-SnO catalyst.
NH-SCR 性能被探索与通过一步合成方法制备的低维三元 Mn 基催化剂的结构形态和物理化学性质之间的关系。由于其强氧化性能，Sn-MnOx 容易与 NO、NH 和 O 之间发生副反应，导致更多的 NO 和 NO 的生成，这里大部分 NO 是来自 NH 的非选择性氧化，而一小部分则来自 NH 和 NO 之间的副反应。Co 或 Ni 掺杂到 Sn-MnOx 中作为固溶体组分，明显增强了电子相互作用，有利于活性迁移，并显著降低了副反应对 NO 的选择性倾向，从而减弱了氧化性能。最佳改性导致表面面积增加，并增强了多价阳离子在 Co/Ni-Mn-SnO 之间的强相互作用，提供更多表面吸附氧、Mn 和 Mn 的活性位、高含量 Sn 和丰富的路易斯酸度，以获得更多活性中间体，这显著拓宽了 Sn-MnOx 的活性窗口，通过抑制 NO 的形成提高了 N 的选择性，并对水和硫的抗性也有一定的贡献。在低温反应温度下，三种催化剂上的 SCR 反应主要通过吸附 l-NHx（x=3、2、1）和 B-NH 与气态 NO 的反应来遵循典型的 Elye-rideal（E-R）路线，生成 N 和 NO 副产物。除了上述基本的 E-R 反应之外，随着反应温度的升高，主要的吸附 NOx 物种是双齿硝酸盐，它们也可以在 Langmuir-Hinshelwood 反应中与 Co/Ni 改性 Mn-SnO 催化剂上的吸附 l-NHx 物种发生反应。
